
." Process this file with
." groff -man -Tascii pig2vcd.1
."
.TH pig2vcd 1 2012-2020 Linux "pigpio archive"
.SH NAME
pig2vd - A utility to convert pigpio notifications to VCD.

.SH SYNOPSIS

pig2vcd </dev/pigpioXX >file.VCD
.SH DESCRIPTION


.ad l

.nh
pig2vcd is a utility which reads notifications on stdin and writes the
output as a Value Change Dump (VCD) file on stdout.

.br

.br
The VCD file can be viewed using GTKWave.

.br

.br
.SS Notifications
.br

.br
Notifications consist of 12 bytes with the following binary format.

.br

.br

.EX
typedef struct
.br
{
.br
   uint16_t seqno;
.br
   uint16_t flags;
.br
   uint32_t tick;
.br
   uint32_t level;
.br
} gpioReport_t;
.br

.EE

.br

.br
seqno: starts at 0 each time the handle is opened and then increments by one for each report.

.br

.br
flags: two flags are defined, PI_NTFY_FLAGS_WDOG and PI_NTFY_FLAGS_ALIVE. If bit 5 is set (PI_NTFY_FLAGS_WDOG) then bits 0-4 of the flags indicate a gpio which has had a watchdog timeout; if bit 6 is set (PI_NTFY_FLAGS_ALIVE) this indicates a keep alive signal on the pipe/socket and is sent once a minute in the absence of other notification activity.

.br

.br
tick: the number of microseconds since system boot. It wraps around after 1h12m.

.br

.br
level: indicates the level of each gpio. If bit 1<<x is set then gpio x is high. pig2vcd takes these notifications and outputs a text format VCD.

.br

.br
.SS VCD format
.br

.br
The VCD starts with a header.

.br

.br

.EX
$date 2013-05-31 18:49:36 $end
.br
$version pig2vcd V1 $end
.br
$timescale 1 us $end
.br
$scope module top $end
.br
$var wire 1 A 0 $end
.br
$var wire 1 B 1 $end
.br
$var wire 1 C 2 $end
.br
$var wire 1 D 3 $end
.br
$var wire 1 E 4 $end
.br
$var wire 1 F 5 $end
.br
$var wire 1 G 6 $end
.br
$var wire 1 H 7 $end
.br
$var wire 1 I 8 $end
.br
$var wire 1 J 9 $end
.br
$var wire 1 K 10 $end
.br
$var wire 1 L 11 $end
.br
$var wire 1 M 12 $end
.br
$var wire 1 N 13 $end
.br
$var wire 1 O 14 $end
.br
$var wire 1 P 15 $end
.br
$var wire 1 Q 16 $end
.br
$var wire 1 R 17 $end
.br
$var wire 1 S 18 $end
.br
$var wire 1 T 19 $end
.br
$var wire 1 U 20 $end
.br
$var wire 1 V 21 $end
.br
$var wire 1 W 22 $end
.br
$var wire 1 X 23 $end
.br
$var wire 1 Y 24 $end
.br
$var wire 1 Z 25 $end
.br
$var wire 1 a 26 $end
.br
$var wire 1 b 27 $end
.br
$var wire 1 c 28 $end
.br
$var wire 1 d 29 $end
.br
$var wire 1 e 30 $end
.br
$var wire 1 f 31 $end
.br
$upscope $end
.br
$enddefinitions $end
.br

.EE

.br

.br
The header defines gpio identifiers and their name.  Each gpio identifier
must be unique.  pig2vcd arbitrarily uses 'A' through 'Z' for gpios 0
through 25, and 'a' through 'f' for gpios 26 through 31.
The corresponding names are 0 through 31.
.br

.br

.br
The VCD file may be edited to give a frendlier name, e.g. 8 could be
changed to ENCODER_A if an encoder switch A is connected to gpio 8.

.br

.br
Following the header pig2vcd takes notifications and outputs a timestamp
followed by a list of one or more gpios which have changed state.
The timestamp consists of a '#' followed by the microsecond tick.
The state lines contain the new state followed by the gpio identifier.

.br

.br

.EX
#1058747
.br
0H
.br
0I
.br
#1059012
.br
1H
.br
#1079777
.br
1I
.br
#1079782
.br
0I
.br
#1079852
.br
1I
.br
#1079857
.br
0I
.br
0H
.br
#1165113
.br
1H
.br
#1165118
.br
0H
.br
#1165153
.br
1H
.br

.EE

.SH SEE ALSO

pigpiod(1), pigs(1), pigpio(3), pigpiod_if(3), pigpiod_if2(3)
.SH AUTHOR

joan@abyz.me.uk
